8o

r Orionis (A-B.), (B-C.), (A-D.) 15', 2", 20' 250' Procyon ...

4 Delphini

X Aquilse ^A-C.) ...

a2 Capricorni

5 Monocerotis k Leonis (A-C.) o 2 24 (Bum. 235) Cassiop.

2", 20' 250°, 550, 64° 4, 15, 16, 12

42' 3120 1, 17

10' 359° 4'5> 17

i'7 360° 6, 17

(A-BC.) 6", i#>5 (B-C) 145° 250° 3, 14, 16

35" 30° 4'5> 17

45" 30° 5> 18

288°. 67°, 8o°, 490 A 7, B ni, C ni,bi8, C17

/, 30" (A-C.) 170° 3320 4-5 (var.), 18, 18

12" 170 3b 18

5" 6o° 3b 18

10" 320° 4‘5. 18

20"~h 232°-!- 6, 20

76", 5" (B-C.) 3°7° 1, 8-5, 20

46"-!- 270°± 3, 20

r\ Cygni ... ... (A-B/

/3 Aquilse...

£ Aquilse... a2 Cancri... a Coronse (A-C.) ...

Regulus ... ... (A-B

/3 Lyrse ...

The first seven stars should be

,, twenty-one or twenty-two ,., six-and-a-half inch telescope.

,, twenty-five ,, eight-and-a-half inch telescope.

The remaining stars on the list will be found good tests for telescopes of from nine to fourteen or fifteen inches aperture.

The magnitudes given are expressed according to Herschel's scale, but those of the smaller stars on the list are necessarily liable to considerable uncertainty.

For the above lists I am indebted to the great kindness of Mr. Herbert Sadler.

HORNE AND THORNTHWAITE have received many Testimonials from Astronomers who possess Telescopes of their manufacture, copies of which may be had on application They have selected the following letters from the same gentleman as indicating what may be seen with silvered-glass speculum of moderate aperture.

Cheltenham, December, 1876.

I have reason to congratulate you and myself on the definition of, the 8^-inch mirror. On some few occasions I have been so fortunate as to have been observing under very favourable atmospheric conditions, when nothing could exceed the sharpness and beauty of the image afforded by Saturn. The companions of Rigel, Aldebaran, and Vega were very apparent with a full moon. I could see the four companions to (3 Equulei, two to the north and two (far fainter) to the south, r Arietis proved a very easy object and 36 Andromeda; was readily separable. The lunar views were, on several occasions, exquisitely sharp and beautiful, even with my highest power, over 500. G. F.

Cheltenham, February, 1877.

Since my last writing to you I have enjoyed several good observing nights, and am, in consequence, still more convinced of my great indebtedness to you for the beautifully defining and powerful instrument now in my possession. With my highest power, 530, I have had several magnificent views of lunar objects. With its aid I have been able to see and delineate nearly as much of the crater Gassendi as was drawn by Madler, with the aid of the Dorpat Achromatic. I have had several clear views of the 6th star in Trapezio, and have well divided <p Draconis and y2 Andromeda; with 350 and 5^-inch stop. Even this reduced aperture gives me decidedly more light than is afforded by a very excellent 4j-inch Cooke Achromatic possessed by a friend. G. F.

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